| 1. |
- Niblaeus, Carl, et al.
(author)
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Effect of polarisation and choice of event generator on spectra from dark matter annihilations
- 2019
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In: Journal of Cosmology and Astroparticle Physics. - : IOP Publishing. - 1475-7516. ; :10
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Journal article (peer-reviewed)abstract
- If indirect detection searches are to be used to discriminate between dark matter particle models, it is crucial to understand the expected energy spectra of secondary particles such as neutrinos, charged antiparticles and gamma rays emerging from dark matter annihilations in the local Universe. In this work we study the effect that both the choice of event generator and the polarisation of the final state particles can have on these predictions. For a variety of annihilation channels and dark matter masses, we compare yields obtained with Pythia8 and Herwig7 of all of the aforementioned secondary particle species. We investigate how polarised final states can change these results and do an extensive study of how the polarisation can impact the expected flux of neutrinos from dark matter annihilations in the centre of the Sun. We find that differences between the event generators are larger for yields of hadronic end products such as antiprotons, than for leptonic end products. Concerning polarisation, we conversely find the largest differences in the leptonic spectra. The large differences in the leptonic spectra point to the importance of including polarisation effects in searches for neutrinos from dark matter annihilations in the Sun. However, we find that these differences are ultimately somewhat washed out by propagation effects of the neutrinos in the Sun.
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| 2. |
- Niblaeus, Carl, et al.
(author)
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Neutrinos and gamma rays from long-lived mediator decays in the Sun
- 2019
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In: Journal of Cosmology and Astroparticle Physics. - : IOP Publishing. - 1475-7516. ; :11
-
Journal article (peer-reviewed)abstract
- We investigate a scenario where dark matter (DM) particles can be captured and accumulate in the Sun, and subsequently annihilate into a pair of long-lived mediators. These mediators can decay further out in the Sun or outside of the Sun. Compared to the standard scenario where DM particles annihilate directly into Standard Model particles close to the solar core, here we also obtain fluxes of gamma rays and charged cosmic rays. We simulate this scenario using a full three-dimensional model of the Sun, and include interactions and neutrino oscillations. In particular, we perform a model-independent study of the complementarity between neutrino and gamma ray fluxes by comparing the recent searches from IceCube, Super-Kamiokande, Fermi-LAT, ARGO and HAWC. We find that the resulting neutrino fluxes are significantly higher at high energy when the mediators decay further out in the Sun. We also find that gamma ray searches place stronger constraints than neutrino searches on these models even in cases where the mediators decay mainly inside the Sun, except in the approximately inner 10% of the Sun where neutrino searches are more powerful. We present our results in a model-independent manner and release a new version of the WimpSim code that can be used to simulate this scenario for arbitrary mediator models.
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| 3. |
- Niblaeus, Carl, 1988-
(author)
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Studies of dark matter annihilation and production in the Universe
- 2019
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Doctoral thesis (other academic/artistic)abstract
- In this PhD thesis we investigate various aspects of particle dark matter. The proper identification of dark matter developed during the second half of the twentieth century to become one of the biggest endeavours in modern physics and astronomy. Although observations currently favour the explanation that dark matter consists of a new form of particle, no experimental search has yet provided unequivocal evidence of such a particle. Of particular importance in this thesis is the field of indirect detection of dark matter, where one searches for the particles emerging from annihilations of dark matter particles out in the Universe. Specifically, we consider dark matter annihilations in the centre of the Sun. As the Sun moves through the galaxy, some dark matter particles scatter in the Sun and lose enough energy to become bound to the Sun. They settle in the solar core and begin to annihilate, which leads to an annihilation signal from the solar direction.The thesis is built on novel research consisting of three papers and a monograph-type chapter. In the first paper we calculate the flux of high energy neutrinos coming from cosmic ray cascades in the solar atmosphere and investigate the role it plays as a background in solar dark matter searches. In the second paper we consider dark matter annihilating into long-lived mediators in the Sun, which leads to interesting new detection possibilities. A third paper explores more generally the fluxes of secondary particles from dark matter annihilations that are searched for in indirect detection. We look at the effects of changing the Monte Carlo event generator that generates the fluxes and of having polarized final states in the annihilations. Finally, we consider in a monograph-type chapter the production of dark matter in the early Universe through the freeze-out mechanism, looking at effects of higher order corrections in the calculation of the relic abundance in the minimal supersymmetric standard model.
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